Masking device and coating method

ABSTRACT

Masking means ( 1 ) for masking of a longitudinally extended edge area of a vehicle body or an appliance housing during a coating process, in particular a painting or preservation process, with the arrangement of a longitudinally continuous cavity and slot ( 3 ) of the outer contour leading into it, whose boundary areas are elastically pre-tensioned to each other.

The invention is a masking means according to the generic term of claim1 as well as a coating procedure performed with said masking means, inparticular a painting or conservation procedure according to the genericterm of claim 17.

The automobile painting process is currently one of the mosttechnologically demanding paint applications. The most important demandsare colour effect and gloss as well as protection of the metal surfacesfrom the elements. The desired properties of the paint are attained viathe functional layer composition, in which the individual layers servedifferent purposes. First a cathodic dip-coating (CDC) is applied as ananti-corrosion layer on the body shell, which coating is burned in adrying oven at temperatures of up to 220 degrees Celsius. Only then doesthe primed body go on to the actual coating process, the first step ofwhich is to apply a filler to even out the foundation and for protectionagainst falling rocks. A base coat is then applied for colouring andspecial effects, and finally a clear coat for protection from externalforces. The actual painting process carried out after the CDC layer isperformed at temperatures of up to approx. 175° C.

After being run through the coating line, internals on the body of avehicle are implemented. In particular, the window panes (windscreen,back window and fixed side windows) in large-scale production aregenerally installed and adhered robotically on the installation site(direct glazing). The window adhesive is first applied in beads aroundthe border area of the window pane, before this area is brought intocontact with and pressed onto the body flange (window flange) at theinstallation opening. The structural connection between the window andthe body serves both for stabilization in the sense of atorsion-resistant body as well as force deflection in the event of acrash.

Since all layers sprayed on in the coating process, such as filler coatand topcoat, are applied according to the demands of the client, it isnecessary that the window adhesive achieves good adhesion on manydifferent topcoats (colours). However, the structural connection betweenthe window and body in the assembly, where the coated surfaces are, isnot adequately removed because the coat structure cannot bear thestructural forces, particularly in a crash. Thus, in order to achievegood adhesion between the body flange and the window adhesive, it isoptimal to adhere the windows on the CDC layer because this eliminatesthe structural weaknesses in the filler coat and topcoat. This kind ofstructural adhesion supports the lightweight construction trend andincreases the torsion-resistance of the body. Though this procedure alsorequires a necessary masking of the body flange after running throughthe CDC coating to keep the coating layers applied in the subsequentcoating steps away from this area. The masking provides flawlessadhesion of the window adhesive to the CDC coated flange.

There is a well-known procedure for window adhesion in which the bodyflange is masked with an adhesive strip or with an organic mass, such asa PVC plastisol. The plastisol is set e.g. via IR radiation or in a PVCoven and thus attains a solid consistency. At the end of the coatingprocess and before the installation of the windows, the flange maskingis usually removed again and disposed of manually and the direct glazingis applied to the CDC coated flange. Neither the plastisol nor theadhesive strip is recyclable, which means that the disposal of the wastefrom the procedure is necessary to a considerable degree.

For this reason, the subject of a prior patent application(PCT/EP01/07501) from the applicant was an improved means (maskingmeans) for the replacement of the adhesive strip. This means is aninjection-moulded synthetic component applicable to the CDC coat withpositive-locking. It is considerably easier to maintain than theaforementioned adhesive strip and is recyclable, which eliminatesdisposal costs and expenditures.

The object of this invention is to provide a further improved maskingmeans of this kind, which in particular is economical to manufacture andcan be easily maintained in various application situations.

This object is attained by a masking means with the features of claim 1.Appropriate further development of the idea of the invention is thesubject of the attached claims. Moreover, this framework provides animproved coating procedure.

The design of the masking means as an extruded synthetic profile offersconsiderable cost savings in comparison to an injection-moulding part.Furthermore, the provision of the masking means as semi-continuousprofile is conducive to a wide range of applications, since the maskingmeans can be simply and easily adapted to the most distinct and unusualapplication situations by cutting it to suitable length.

In one of the currently favoured embodiments, the synthetic profile hasbeen developed in cross-section in essentially circular, elliptical,oval or slanted oval shapes and as synthetic corrugated pipe withgreater rigidity and lower elasticity in first portions and lowerrigidity and greater elasticity in second portions.

O-form synthetic profiles are well-known from other areas of technology,for instance as “current-cable hoses”, and predominantly manufacturedwith the rotation extrusion procedure. Therefore, in principle, thismasking means has established manufacturing technology and commerciallyavailable manufacturing plants. This greatly facilitates practicalintroduction in the cost parameters prescribed by the pressure of costsin large-scale automotive production. A masking means of thisdesign-type is flexible (assuming the proper material and dimensioning)to such a high degree that the demands on the window flange masking inautomobile coating can be met without limitation.

For special applications, it is a good idea, for further development inthis design of the invention, that an additional bracket be provided toincrease the contact pressure of the masking profile, particularlysynthetic corrugated pipes, on the corresponding body section. This kindof bracket has a portion with an internal cross-section adapted to theexternal form of the masking profile and a sufficiently large openingwhich allows lateral movement on the masking profile in its stateadapted to the body section. The favoured design also features anoperation section for easy gripping of the bracket.

In particular, for other profile designs which do not attain such a highdegree of flexibility in the primary moulding, an additional treatmentis necessary for increased longitudinal flexibility. It is advantageous,for instance, to provide cuts that are tilted with respect to the longaxis and longitudinally equidistant, which cut through the side of theprofile in the large part of the level of the synthetic profile, for thecreation of profile tabs joined together opposite the slot that tiltagainst each other but still essentially cover each other in areas oftight bending.

Depending on the specific technological formulation of the procedure formanufacture of cover profiles, a design in which the aforementioned cutsare not provided in the same sections or in which no cuts at all areprovided over longer profile sections may be appropriate. If we haveprofile manufacturing controls adapted to a specific body shape, theprovided curved areas of the profile can be shaped in this respectdifferently from the profile sections which will cover longitudinallyextended edge areas.

This design with the aforementioned profile tabs (which could be viewedas a kind of fish scale) is particularly prudent in connection with analternative profile design for the “synthetic corrugated pipe” mentionedabove, in which the synthetic profile in cross-section essentially has aU-shape, in particular a “U” with sides of different lengths. Thisembodiment is in turn particularly favoured for further development inwhich the synthetic profile in cross-section has the form of a slanted“U” with a cavity expanding on the basis of the “U” for theelastically-bonded attachment on the edge area with different materialthicknesses. The aforementioned U profile is suitable in a single designfor practically all applications in the automobile coating sector, butalso for other possible applications with different plate densities, forexample in the coating of home appliances or industrial systems.

Considerable material savings are particularly possible with profiledesigns with partial relatively high lateral strengths, such as therecently mentioned slanted “U”, if the longitudinal side of thesynthetic profile exhibits continuous, closed cavities for increasingthe flexibility and decreasing the amount of material used.

For the aforementioned applications which have priority under thecurrent viewpoint, a suitable synthetic profile design is one in whichthe cavity has a maximum width in the range of 3 to 12 mm and thecontinuous slot has a minimum free width of less than 1 mm, especiallyof 0.2 mm or less, for the elastically-bonded attachment on an edgearea, particularly body/housing flange, with a minimum materialthickness of roughly 0.5 mm and a maximum material thickness up to therange of 2.5 to 6 mm (depending on the profile construction).

In view of the temperatures occurring in the coating layers of theautomobile production line, designs with high-gradetemperature-resistant plastic are further favoured, which maintain themasking means properties that are essential to functioning at at least175° C. for at least 25 min and further at least 155° C. for at least 75min.

At any rate, for certain variations, such as the designs as essentially“smooth” U profiles, reinforcement via filler material with a quantitybetween 0.1% and 40% is functional. From the perspective of easymanufacture and handling, designs with a thermoplastic elastomer orpolyamide are further favoured. In addition, plastics such aspolysulphone and poly(arylether)ketone come under consideration, asindicated in A. Frank, Kunstoffkompendium, Vogel Fachbuch, fourthedition, 1996. For reinforcement material, for reasons related to cost,we particularly consider glass fibres, for special applications alsocarbon and synthetic fibres.

For environmental reasons, we favour a design of the masking means witha considerable quantity, in particular more than 75% and moreparticularly 90%, of recycled plastic. The designs can establish anessentially closed material flow cycle for the manufacturer of this kindof equipment and pose practically no disposal problems.

The proposed new type of masking means is not only applicable withcoating or conservation processes in automotive or device construction(especially home appliance or entertainment electronics production).Rather, it also has other possible applications in the framework ofliquid or powder spray processes, in which edges and/or openings of aproduct component—in particular, but not excluded to, part of thehousing—must be protected before setting down the medium being applied.In principle, its application is therefore also possible in anadvantageous manner in vacuum coating processes, and thus in particularhigh-vacuum vapour deposition processes and sputter processes.

The advantages and functionalities of the invention can be further seenfrom the claims below as well as the following description of twofavoured designs based on the figures. These show:

FIG. 1A to 1C different views (side view, front view and top view) of amasking means according to an initial design of the invention, appliedto a bent window flange,

FIG. 2A to 2C Front views of designs of the masking means that areslightly modified in their particular form according to FIG. 1A to 1C,the latter also in an installation situation on an automobile tailgatepanel,

FIGS. 3A and 3B Outline representation of a bracket appropriate forapplication with a masking means as per FIG. 1 a to 2B, in perspectiverepresentation and/or representation of an installation situation,

FIG. 4 a series of schematic cross-section representations of a maskingmeans according to an additional design in different states, whichfeatures plates of different thickness, and

FIG. 5A to 5C Side views of the two sides (FIGS. 3A and 3C) as well as atop view of a masking means of the kind illustrated in FIG. 2, which isbent on one end in a very small radius.

FIG. 1A to 1C show a masking profile 1 manufactured via rotationextrusion in the form of a synthetic corrugated pipe, which exhibits alongitudinal slot 3 with V shaped mounting area 5. The syntheticcorrugated pipe consists of integral, alternately ordered first rings 7Awhich are formed together, with larger diameters and two rings 7B withsmaller diameters (which under certain conditions can exhibit lowlateral strength and therefore high flexibility like the first rings7A).

The outer diameter of the first rings 7A in the currently favoureddesign is between 16 and 20 mm, those rings of smaller diameter, ifapplicable, between 9 and 13 mm and the lateral strength at approx. 0.5mm. The longitudinal slot 3 has a width of approx. 0.1 to 0.2 mm and theV shaped boundaries of the mounting area 7 which are-tilted toward eachother, meet at an angle of roughly 60 to 75°.

FIGS. 2A and 2B show a front view and profile cross-section,respectively, of modified synthetic corrugated pipe, 1′ and 1″,respectively. In profile 1′ represented in FIG. 2A, the mounting area(not denoted separately here) is gently rounded and relatively flat indesign, and the profile shape on the whole is somewhat levelled off withthe circular cross-section. In the masking means 1″ represented in FIG.2B, the outer contour in the cross-section is nearly circular and themounting area is designed in a distinctive, clearly offset V shape. FIG.2C shows the synthetic corrugated pipe 1″ in the states set up on theedge area of an automobile tailgate panel 8.

FIGS. 3A and 3B show a bracket 9 as additional element of a maskingsystem when using a synthetic corrugated pipe in one of the designsdescribed above, in order to increase its holding force on thebody/housing section being covered. The bracket 9 has a roughlyglasses-type basic form with a first, almost circular section 9 a, whichfunctions as a contact and holding section relative to a syntheticcorrugated pipe, and a second circular (but entirely closed) section 9b, which serves as handling section in the set up of the bracket on acorrugated pipe and/or-the removal of this. The two sections, 9 a and. 9b, are linked together by a web 9 c. Of course that opening 9 d in thecontact and holding section 9 a is adapted to the outer cross-section ofthe synthetic corrugated pipe in such a way that the bracket can bemoved laterally over it relatively easily, on the other hand, this alsoreliably prevents it from coming off or from unintentional removal. Thefigures also demonstrate that, in the designs given here, the circularcross-section of the contact and holding section 9 a is smaller, thoughits width is greater than that of the handling section 9 b.

FIG. 4 to 5C show an alternative masking means design for syntheticcorrugated pipe 1, viz., an extruded seal profile 11. It can be easilyseen in FIG. 4 that this profile in the cross-section shape could bedescribed as “slanted U-shaped”, since, from a base 13, a first, upwardtapering side piece 15 and a second side piece 17 extend out in anasymmetrically tilting manner. Both of pieces, 15 and 17, exhibit anoutward unwind, 15 a and 17 a, on their outer ends. As can also be seenin FIG. 4, this shape is excellently suited for secure mounting of theseal profile 11 on plates of widely differing thicknesses, anti-fogcovering of the plate surface near the edges which is under (in thefigure on the left) the side piece.

One can easily see in FIGS. 5A and 5C, how the height of the thoroughlyexecuted cuts of the seal profile 11 that is ordered by diagonal to thelongitudinal axis, is subdivided into individual layers or “scales”,which are only connected with each other on a relatively narrow,strip-shaped profile section. FIGS. 5A and 5C show, viewed from longeror shorter side pieces 15 or 17, how these layers spread apart whenprofile 11 is bent in a small radius. One will also notice that thelonger profile side piece 15 also attains a very god covering of anunderlying strip-shaped area (flange) in this extreme position ofprofile 11, as it occurs, for instance, in the “corners” of a windowflange.

Both masking profiles 1 and 11 of the aforementioned first and seconddesigns have as fundamental shared features a longitudinal slot, whichexpands into a cavity for the interior of the profile. In both designs,the sides of the slot are automatically pre-tensioned with respect toeach other in a bracket-like way, so that the profile is automaticallyheld in place by the friction force on a flange or other plate strip, onwhich it is slid open. It is common to both designs that the slotexpands a bit more toward the periphery of the profile, whichfacilitates the attachment on the edges to be covered.

The design of the invention is not restricted to these examples, butalso has numerous other possible adaptations within the framework oftechnical commerce. In particular, adaptations in the form of the twoindicated masking profiles must be considered to exist for a wide arrayof variations as in the framework of the invention.

KEY TO NUMBER REFERENCES

-   1;1′;1″ Masking Profile-   3 Longitudinal slot-   5 Mounting Area-   7A First Ring-   7B Automobile Tailgate Panel-   9 Bracket-   9 a Contact and Holding Section-   9 b Handling Section-   9 c Web-   9 d Opening-   11 Seal Profile-   13 Base-   15, 17 Side Pieces-   15 a, 17 a Unwind Area

1. Masking means for masking of a longitudinally extended edge area of avehicle body or an appliance housing during a coating procedure, inparticular a paint or conservation process, wherein the development isas longitudinal high-grade flexible extruded synthetic profiles with acontinuous longitudinal cavity and a slot in the outer contour leadinginto the cavity, whose boundary edges are elastically pre-tensioned toeach other.
 2. Masking means according to claim 1, wherein the syntheticprofile design is in the cross-section essentially circular, elliptical,oval or slanted oval and as synthetic pipe with longitudinallyalternating first portions of greater rigidity and lower elasticity andsecond portions of lower rigidity and greater elasticity.
 3. Maskingmeans according to claim 2, wherein the synthetic profile design isformed, via a rotation extrusion procedure, with longitudinallyalternating first portions of greater rigidity and lower elasticity andsecond portions of lower rigidity and greater elasticity.
 4. Maskingmeans according to claim 1, wherein the synthetic profile in the slotarea is essentially retracted V or U-shaped such that it automaticallyaligns itself on the longitudinally extended edge area when slid ontoit.
 5. Masking means according to claim 1, wherein longitudinallyequidistant incisions are provided that are diagonal to the long axis,which cut through the profile side at the large part of the level of thesynthetic profile, for the formation of profile tabs joined togetheropposite the slot that tilt against each other but still essentiallycover each other in areas of tight bending.
 6. Masking means accordingto claim 1, wherein the synthetic profile in the cross-sectionessentially has a U-shape, in particular with a “U” with side pieces ofdifferent lengths.
 7. Masking means according to claim 6, wherein thesynthetic profile in cross-section has the form of a slanted “U” with acavity expanding on the basis of the “U” for the elastically-arrestedattachment on the edge area with different material thicknesses. 8.Masking means according to claim 1, wherein the wall of the syntheticprofile exhibits continuous, closed cavities extending in longitudinaldirection, for increasing the flexibility and decreasing the amount ofmaterial used.
 9. Masking means according to claim 1, wherein the cavityhas a maximum width in the range of 3 to 12 mm and the continuous slothas a minimum free width of less than 1 mm, especially of 0.2 mm orless, for the elastically-arrested attachment on an edge area,particularly body/housing flange, with a minimum material thickness ofroughly 1 mm and a maximum material thickness within the range of 2.5 to6 mm.
 10. Masking means according to claim 1, wherein the design is withhigh-grade temperature-resistant plastic, which maintains the maskingmeans properties that are essential to functioning at least 175° C. forat least 25 min and also at least 155° C. for at least 75 min. 11.Masking means according to claim 1, wherein reinforcement is via fillermaterial with a quantity between 0.1% and 40%.
 12. Masking meansaccording to claim 11, wherein the design is with a thermoplasticelastomer or polyamide.
 13. Masking means according to claim 11, whereina considerable quantity, in particular more than 75% and moreparticularly 90%, is of recycled plastic.
 14. Masking arrangement with amasking means according to one of the above claims and a bracketattachable to the masking means for improved adhesion on the edge area.15. Masking arrangement according to claim 14, wherein the bracketexhibits a contact and holding section in its inner contour on the outercontour of the masking means as well as handling section connected withthis, particularly via a web.
 16. Masking arrangement according to claim14, wherein the contact and holding section and/or the handling sectionof the bracket essentially exhibits circular, elliptical or ovalcross-section.
 17. Coating process for coating a coating substrate, inparticular a vehicle body or an aircraft fuselage or ship's hull or anappliance housing having a free edge area, with a coating means via acoating-spray stream or under a coating atmosphere, under coverage ofthe edge area, wherein the edge area is covered with a masking meansaccording to one of the above claims.
 18. Coating process according toclaim 17, wherein the process is embodied as a procedure for thepainting of a dip primer coated vehicle body or an appliance housing viaa paint-spray stream.
 19. Coating process according to claim 17, whereinthe process is embodied as a process, in particular which is directlycarried out after a painting process, for the conservation of a vehiclebody or appliance housing, in particular an automobile body or anaircraft fuselage or ship's hull, via a conservation-spray stream. 20.Coating process according to claim 17, wherein the process is embodiedas a vacuum coating process, in particular vacuum sputter or sputterprocesses, for creation of a thin protective or functional coating onthe coating substrate.